Photoacid generator systems for short wavelength imaging

ABSTRACT

New photoacid generator systems that comprise a sensitizer compound and one or more photoacid generator compounds are provided and photoresist compositions that comprise such systems. Photoacid generator systems of the invention are particularly useful as photoactive components of photoresists imaged at short wavelengths such as 248 nm, 193 nm and 157 nm.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to new photoacid generator (“PAG”) systemsand photoresist compositions that comprise such systems. PAG systems ofthe invention in, general comprise one or more photoacid generatorcompounds and one or more sensitizer compounds. PAGs of the inventionare preferably employed in resists imaged at short wavelengths, such assub-200 nm, e.g. 193 nm and 157 nm.

[0003] 2. Background

[0004] Photoresists are photosensitive films for transfer of images to asubstrate. They form negative or positive images. After coating aphotoresist on a substrate, the coating is exposed through a patternedphotomask to a source of activating energy such as ultraviolet light toform a latent image in the photoresist coating. The photomask has areasopaque and transparent to activating radiation that define an imagedesired to be transferred to the underlying substrate. A relief image isprovided by development of the latent image pattern in the resistcoating. The use of photoresists is generally described, for example, byDeforest, Photoresist Materials and Processes, McGraw Hill Book Company,New York (1975), and by Moreau, Semiconductor Lithography, Principals,Practices and Materials, Plenum Press, New York (1988).

[0005] Known photoresists can provide features having resolution andsize sufficient for many existing commercial applications. However formany other applications, the need exists for new photoresists that canprovide highly resolved images of submicron dimension.

[0006] Various attempts have been made to alter the make-up ofphotoresist compositions to improve performance of functionalproperties. Among other things, a variety of photoactive compounds havebeen reported for use in photoresist compositions. See, e.g., U.S. Pat.No. 4,450,360 and European Application 615163.

[0007] More recently, certain “chemically amplified” photoresistcompositions have been reported. Such photoresists may benegative-acting or positive-acting and rely on multiple crosslinkingevents (in the case of a negative-acting resist) or deprotectionreactions (in the case of a positive-acting resist) per unit ofphotogenerated acid. In other words, the photogenerated acid actscatalytically. In the case of positive chemically amplified resists,certain cationic photoinitiators have been used to induce cleavage ofcertain “blocking” groups pendant from a photoresist binder, or cleavageof certain groups that comprise a photoresist binder backbone. See, forexample, U.S. Pat. Nos. 5,075,199; 4,968,851; 4,883,740; 4,810,613; and4,491,628, and Canadian Patent Application 2,001,384. Upon selectivecleavage of the blocking group through exposure of a coating layer ofsuch a resist, a polar functional group is provided, e.g., carboxyl,phenol or imide, which results in different solubility characteristicsin exposed and unexposed areas of the resist coating layer.

SUMMARY OF THE INVENTION

[0008] We have now discovered novel photoacid generator systems for usein either positive-acting or negative-acting photoresist compositions.

[0009] We have found that excessive absorbance can remain an issue forresists imaged at short wavelengths such as 193 nm, even where theresist resin is optimized for low absorbance such as by having little orno aromatic content. In particular, we have found that a targetedabsorption “budget” for a short wavelength resist may be substantiallyconsumed by the resin component alone.

[0010] Photoacid generator systems of the invention in general compriseone or more photoacid generator compounds and one or more sensitizercompounds. The sensitizer component can be integral (covalently linked)to another resist component, such as the resin or PAG, but moretypically the sensitizer is a separate resist additive.

[0011] Preferred sensitizer compounds are aromatic systems, bothheteroaromatic and carobcyclic aryl, including compounds that compriseseparate and/or fused multi-ring aromatic systems. Preferred sensitizercompounds are electron rich and comprise one or more electron-donatingsubstituents, such as e.g. optionally substituted alkyl preferablyhaving 1 to about 20 carbon atoms, optionally substituted alkoxypreferably having 1 to about 20 carbon atoms, optionally substitutedthioalkyl preferably having 1 to about 20 carbon atoms, optionallysubstituted thioalkoxy preferably having about 1 to 20 carbon atoms,hydroxy, optionally substituted thiohydroxyalkyl preferably having 1 toabout 20 carbon atoms, and the like. Exemplary preferred sensitizercompounds are discussed below.

[0012] Sensitizer compound(s) can be employed in a resist in quite smallamounts and thus can positively impact efficiency (i.e. photoacidgeneration) of the PAG component without unduly adding to the overallabsorbance of the resist.

[0013] In fact, it has been found that addition of a sensitizercomponent can dramatically increase the sensitivity of a PAG componentto short wavelength radiation, particularly sub-200 nm radiation such as193 nm.

[0014] Preferred PAGs for use in the PAG systems of the invention canexhibit good transparency without significant loss ofphotoacidgeneration efficiency upon exposure to short wavelengthradiation such as 193 nm.

[0015] Preferred PAGs for use in the PAG systems of the inventioninclude sulfonium and iodonium compounds having a cation component thatcomprises one or more substituents of naphthyl, thienyl, orpentafluorophenyl, or a cation component that has a sulfur ring groupsuch a thienyl, benzothiophenium, etc. Those substituents (chromophores)provide enhanced transparency of the PAG, while maintaining effectivephotoacid generation properties.

[0016] Additional preferred PAGs for use in the PAG systems of theinvention include oxime sulfonate PAGs, preferably where the oximecarbon has one or two electron-withdrawing substituents. Also preferredare N-oxy-imidosulfonate PAGs that preferably contain contain two ormore N-oxyimidosulfoanate groups in a single PAG compound. Suchcompounds are capable of generating a molar excess of photogeneratedacid per mole of the PAG compound.

[0017] Preferably, PAGs of the invention are used in positive-acting ornegative-acting chemically amplified photoresists, i.e. negative-actingresist compositions which undergo a photoacid-promoted crosslinkingreaction to render exposed regions of a coating layer of the resist lessdeveloper soluble than unexposed regions, and positive-acting resistcompositions which undergo a photoacid-promoted deprotection reaction ofacid labile groups of one or more composition components to renderexposed regions of a coating layer of the resist more soluble in anaqueous developer than unexposed regions. Ester groups that contain atertiary non-cyclic alkyl carbon or a tertiary alicyclic carboncovalently linked to the carboxyl oxygen of the ester are generallypreferred photoacid-labile groups of resins employed in photoresists ofthe invention.

[0018] As discussed above, preferred imaging wavelengths of photoresistsof the invention include sub-200 nm wavelengths e.g. 193 nm and 157 nm.

[0019] Particularly preferred photoresists of the invention contain animaging-effective amount of one or more PAGs (including PAGs of thebelow-discussed formulae) that is selected from the group of:

[0020] 1) a phenolic resin that contains acid-labile groups that canprovide a chemically amplified positive resist particularly suitable forimaging at 248 nm. Particularly preferred resins of this class include:i) polymers that contain polymerized units of a vinyl phenol and analkyl acrylate, where the polymerized alkyl acrylate units can undergo adeblocking reaction in the presence of photoacid. Exemplary alkylacrylates that can undergo a photoacid-induced deblocking reactioninclude e.g. t-butyl acrylate, t-butyl methacrylate, methyladamantylacrylate, methyl adamantyl methacrylate, and other non-cyclic alkyl andalicyclic acrylates that can undergo a photoacid-induced reaction; suchpolymers have been described in U.S. Pat. Nos. 6,042,997 and 5,492,793,incorporated herein by reference; ii) polymers that contain polymerizedunits of a vinyl phenol, an optionally substituted vinyl phenyl (e.g.styrene) that does not contain a hydroxy or carboxy ring substituent,and an alkyl acrylate such as those deblocking groups described withpolymers i) above, such as polymers described in U.S. Pat. No.6,042,997, incorporated herein by reference; and iii) polymers thatcontain repeat units that comprise an acetal or ketal moiety that willreact with photoacid, and optionally aromatic repeat units such asphenyl or phenolic groups, such as polymers as described in U.S. Pat.Nos. 5,929,176 and 6,090,526, incorporated herein by reference.

[0021] 2) a resin that is substantially or completely free of phenyl orother aromatic groups that can provide a chemically amplified positiveresist particularly suitable for imaging at sub-200 nm wavelengths suchas 193 nm. Particularly preferred resins of this class include: i)polymers that contain polymerized units of a non-aromatic cyclic olefin(endocyclic double bond) such as an optionally substituted norbornene,such as polymers described in U.S. Pat. Nos. 5,843,624 and 6,048,664,incorporated herein by reference; ii) polymers that contain alkylacrylate units such as e.g. t-butyl acrylate, t-butyl methacrylate,methyladamantyl acrylate, methyl adamantyl methacrylate, and othernon-cyclic alkyl and alicyclic acrylates; such polymers have beendescribed in U.S. Pat. No. 6,057,083; European Published ApplicationsEP01008913A1 and EP00930542A1; and U.S. pending patent application Ser.No. 09/143,462, filed Aug. 28, 1998, all incorporated herein byreference; iii) and polymers that contain maleic anhydride.

[0022] Resists of the invention also may comprise a mixture of distinctPAGs, typically a mixture of 2 or 3 different PAGs, more typically amixture that consists of a total of 2 distinct PAGs. Photoresists thatcontain such PAG mixtures can exhibit even further enhanced lithographicperformance.

[0023] The invention also provide methods for forming relief images ofthe photoresists of the invention, including methods for forming highlyresolved patterned photoresist images (e.g. a patterned line havingessentially vertical sidewalls) of sub-quarter micron dimensions orless, such as sub-0.2 or sub-0.1 micron dimensions.

[0024] The invention further provides articles of manufacture comprisingsubstrates such as a microelectronic wafer or a flat panel displaysubstrate having coated thereon the photoresists and relief images ofthe invention. Other aspects of the invention are disclosed infra.

DETAILED DESCRIPTION OF THE INVENTION

[0025] As discussed above, the invention provides photoacid generatorsystems for use in either positive-acting or negative-acting photoresistcompositions. Photoacid generator systems of the invention in generalcomprise one or more photoacid generator compounds and one or moresensitizer compounds. The sensitizer component can be integral(covalently linked) to another resist component, such as the resin orPAG component, but more typically the sensitizer is a separate resistadditive.

[0026] Sensitizers

[0027] Preferred sensitizer compounds are carbocyclic aryl orheteroaromatic materials that comprise 1, 2, 3 or 4 separate or fusedaromatic rings. Heteroaromiatic compounds typically contain 1 to about 3N, O or S ring members and from 6 to 18 or more total ring members.Carbocyclic aryl sensitizer compounds also typically contain from 6 to18 carbon ring atoms. Preferably, a sensitizer compound will have one ormore electron-donating ring substituents, typically 1, 2, 3, 4 or 5electron-donating ring substituents, such as e.g. optionally substitutedalkyl preferably having 1 to about 20 carbon atoms, optionallysubstituted alkoxy preferably having 1 to about 20 carbon atoms,optionally substituted thioalkyl preferably having 1 to about 20 carbonatoms, optionally substituted thioalkoxy preferably having about 1 to 20carbon atoms, hydroxy, optionally substituted thiohydroxyalkylpreferably having 1 to about 20 carbon atoms, and the like.

[0028] Sensitizer compounds also may contain a linked separate or fusedring that is non-aromatic rings, such as a ring having from 3 to about 8ring members, particularly cyclopentyl, cyclehexyl, thienyl and thelike.

[0029] Some preferred sensitizer compounds for use in the PAG systemsand resists of the invention include the following:

[0030] Photoacid generator compounds

[0031] A wide variety of photoacid generator compounds can be suitablyemployed in the PAG systems and resists of the invention. Such PAGSinclude onium compounds and non-aromatic PAGS such as imidosulfdonatesand a variety of sulfone (including di-sulfone) PAG compounds.

[0032] As discussed above, particularly preferred PAGs for use in thePAG systems and resits of the invention include sulfonium and iodoniumPAGs vided that contain at least one naphthyl substituent, preferablymultiple naphthyl substituents. Preferred naphthyl-substituted PAGs ofthe invention include sulfonium and iodonium compounds of the followingFormulae I and II:

[0033] wherein in Formulae I and II: each R is the same or differentnon-hydrogen substituent such as hydroxy, cyano, nitro, halogen,optionally substituted alkyl including cycloalkyl; optionallysubstituted alkenyl; optionally substituted alkynyl; optionallysubstituted alkoxy; optionally substituted alkylthio; optionallysubstituted alkylsulfinyl; optionally substituted alkylsulfonyl;optionally substituted alkanoyl; optionally substituted carbocyclicaryl; or optionally substituted heteroalicyclic or heteroaromaticsuitably having 1-3 rings with 3-8 ring members per ring and 1-3 N, O orS atoms;

[0034] each n is an integer equal to 0 (where the naphthyl group has nonon-hydrogen substituents) to 7, more typically 0, 1, 2, 3 or 4; and

[0035] R¹ and R² are the same or different and each is suitably anaromatic or non-aromatic group such as e.g. optionally substituted alkylincluding cycloalkyl; optionally substituted alkenyl; optionallysubstituted alkynyl; optionally substituted alkoxy; optionallysubstituted alkylthio; optionally substituted alkylsulfinyl; optionallysubstituted alkylsulfonyl; optionally substituted carbocyclic aryl; oroptionally substituted heteroalicyclic or heteroaromatic suitably having1-3 rings with 3-8 ring members per ring and 1-3 N, O or S atoms, witharomatic groups typically being preferred R¹ groups;

[0036] X is a counter anion, particularly an organic anion such as asulfonate e.g. of the formula R′SO₃ where R′ is suitably optionallysubstituted alkyl, particularly perfluoroalkyl typically having 1 toabout 12 carbon atoms such as triflate and the like; carbocyclic arylsuch as pentafluorophenylsulfonate; and the like; or X is suitably acarboxylate, e.g. groups of the formula R″COO— where R″ is optionallysubstituted alkyl having 1 to about 18 carbons or optionally substitutedaryl such as phenyl and the like. Preferred substituents of substitutedcarboxylate anions include halo, particularly fluoro.

[0037] Particularly preferred compounds of the above formulae are thosethat have multiple naphthyl groups, such as compounds of the followingFormulae IA, IB, and IIA:

[0038] wherein in each of Formula IA, IB and IIA, R, n, R1 and X are thesame as defined for Formulae I and II above.

[0039] In Formulae I and II, IA, IB and IIA, a naphthyl group may belinked to the iodonium or sulfonium cation at either the 1- or2-naphthyl positions.

[0040] In a further aspect, sulfonium and iodonium PAGs are providedthat contain at least one thienyl substituent. Preferredthienyl-substituted PAGs of the invention include sulfonium and iodoniumcompounds of the following Formulae III and IV:

[0041] wherein in Formulae III and IV: R, R¹ and X are the same asdefined in Formula I and II above;

[0042] in Formula III, m is 1, 2 or 3;

[0043] in Formula IV, m is 1 or 2

[0044] m is 1 or 2 and

[0045] each n is an integer equal to 0 (where the thienyl group has nonon-hydrogen substituents), 1, 2 or 3, preferably 0, 1 or 2.

[0046] Preferred PAGs of Formulae III and IV include compounds that havemultiple thienyl substituents, such as compounds of the followingFormulae IIIA, IIIB, and IVA:

[0047] wherein in Formulae IIIA, IIIB and IVA: each R, R¹, n and X isthe same as defined for Formulae III and IV above.

[0048] In Formulae III, IV, IIIA, IIIB and IVA a thienyl group may belinked to the iodonium atom or sulfonium atom at the 2- or 3-thienylring positions.

[0049] In a further aspect, sulfonium and iodonium PAGs are providedthat contain at least one pentafluorophenyl substituent. Preferredpentafluorophenyl-substituted PAGs of the invention include sulfoniumand iodonium compounds of the following Formulae V and VI:

[0050] wherein in Formula V and VI: R¹ and X are the same as defined inFormulae I and II above;

[0051] in Formula V, m is 1, 2 or 3; and

[0052] in Formula VI, m is 1 or 2.

[0053] Preferred PAGs of Formula V and VI include those that havemultiple pentafluorophenyl groups, such as compounds of the followingFormulae VA, VB and VIA:

[0054] wherein in Formulae VA, VB and VIA: R¹ and X are the same asdefined in Formulae I and II.

[0055] Preferred PAGs of the invention also include sulfonium andiodonium PAGs that contain at least two distinct substituents selectedfrom the group consisting of naphthyl, thienyl and pentafluorophenyl,such as compounds of the following Formulae VII and VIII:

[0056] wherein in Formulae VII, VIII, IX, X, XI and XII: R, R¹, n and Xare the same as defined in Formulae I and II above; and n′ is an integerequal to 0 (where the thienyl group has no non-hydrogen substituents),1, 2 or 3, preferably 0, 1 or 2.

[0057] Preferred R¹ groups of Formulae VII, VIII and IX includepentafluorophenyl, optionally substituted thienyl and optionallysubstituted naphthyl.

[0058] Preferred PAGs for use in the PAG systems and resists of theinvention include sulfonium compounds where the sulfur cation is a ringmember, e.g. a member of a ring having 3 to about 25 atoms (typicallycarbon) and 1 to 3 or 4 separate or fused rings. Thienyl rings aregenerally preferred, suitably optionally substituted, whichsubstitutions can include one or more aromatic or alicyclic rings fusedor otherwise linked to the thienyl ring.

[0059] Such preferred ring sulfonium cation PAGs include those of thefollowing Formula XIII:

[0060] where R¹ and X are the same as defined in Formula I above; thedotted lines designate a ring structure that includes the depictedsulfur cation as a ring member, the ring suitably having 5 to about 8ring members, and one, two or more endocyclic multiple bonds, and one ormore optional substituents, including additional fused rings such as aphenyl or naphthyl that would linked by a single bond or fused to thesulfur cation-ring.

[0061] Generally preferred are compounds where the sulfur cation is amember of a thienyl-based ring system, such as PAGs of the followingFormula XIV:

[0062] wherein R, R1, X and n are each the same as defined in Formula Iabove, and further where two R groups typically on adjacent ring atomsmay together form a fused alicyclic or aromatic ring suitably having 5to about 8 ring members such as optionally substituted phenyl (e.g. toprovide a benzothiophenium group) or optionally substituted naphthylfused to the thienyl group.

[0063] Another preferred group of sulfonium ring PAGs for use in the PAGsensitizer systems and resists of the invention include those of thefollowing Formula XIVA:

[0064] wherein in Formula XIVA, R¹ and X are each suitably the same asdefined in Formula I above; and n is suitably 2 to about 10, moretypically 2 to about 7, and preferably n is 2, 3, 4, or 5; and the ringmay be optionally substituted;

[0065] and the sulfonium ring may be suitably substituted in 1 or morepositions, typically 1, 2 or 3 ring substitutent, by groups as definedfor R¹.

[0066] Preferred compounds of Formula XIVA include those where:

[0067] i) n is 4 and R is optionally substituted naphthyl,pentafluorophenyl, optionally substituted thienyl including optionallysubstituted 2-thienyl and 3-thienyl, and optionally substituted phenyl;and

[0068] ii) n is 5-10 and R is optionally substituted naphthyl,pentafluorophenyl, optionally substituted thienyl including optionallysubstituted 2-thienyl and 3-thienyl, and optionally substituted phenyl.

[0069] However, less preferred compounds of Formula XIVA, and excludedfrom preferred embodiments of the invention, are compounds where n is 4,and R is naphthyl substituted by —O—R₂, particularly 4—O—R₂, where R₂ isH, CH₃, or methylphenol, methoxyphenol, or butylphenol;where n is 5-10.

[0070] Preferred counter anions (group X) of compounds of Formula XIVinclude R₁SO₃ ⁻ where R₁ is haloalkyl such as haloC₁₋₁₂alkylparticularly perhaloalkyl such as perfluoroC₁₋₁₂alkyl,2,2,2-trifluorethyl, camphoryl including 10-camphoryl, optionallysubstituted carbocyclic aryl, cyclo(C₃₋₁₈)alkyl,α,α-difluorocyclo(C₃₋₁₈)alkyl and the like.

[0071] In each of the above formulae, preferably two hetero atoms (N, Oor S) are not adjacent to each other. Thus for example, in Formulae Iand II, if an R1 substituent is alkoxy, preferably the oxygen of thealkoxy is not directly linked to the S⁺ (Formula I) or I⁺ (Formula II)atoms; rather, at least a single carbon spacer (e.g. —CH₂—) will beinterposed between the S⁺ or I⁺ atoms and the oxygen of the alkoxylinkage.

[0072] Preferred R groups of compounds of Formulae I, II, IA, IB, IIA,III, IV, IIA, IIIB, IVA, VII, VIII, IX, X, XI, XII, XIII, XIV and XIVAinclude hydroxy; halogen, particularly F, Cl or Br; optionallysubstituted C₁₋₁₆alkoxy such as methoxy and ethoxy, C₁₋₁₆alkyl such asmethyl, ethyl and perfluoroalkyl such as trifluoromethyl,pentafluoroethyl, etc.

[0073] Preferred R¹ and R² groups of compounds of Formulae I, II, IA,III, IV, IIIA, V, VI, VII, VIII, IX, XIII, XIV, XIV and XIVA includecyclic groups, particularly aromatic groups such as optionallysubstituted carbocyclic aryl such as phenyl, and substituted phenyl suchas halo-phenyl preferably pentafluorophenyl, naphthyl and the like; andheteroaromatic groups such as thienyl and the like. Carbon alicyclic andheteroalicyclic groups also will be suitable R¹ and R² groups such asadamantyl, fenchyl and the like.

[0074] Generally preferred X anion groups of compounds of the aboveformulae are organic anions, including sulfonate and carboxylate anions.Preferred sulfonate X anion groups include those of the formula R′SO₃where R′ is suitably optionally substituted alkyl, particularlyperfluoroalkyl typically having 1 to about 12 carbon atoms such astriflate and the like; carbocyclic aryl such as pentafluorophenylsulfonate; and the like. Preferred carboxylate X groups include those ofthe formula R″COO— where R″ is optionally substituted alkyl having 1 toabout 18 carbons or optionally substituted aryl such as phenyl and thelike. Preferred substituents of substituted carboxylate anions includehalo, particularly fluoro.

[0075] Other suitable anion X groups include aresenic anions such ashalogenated compounds e.g. AsF₆ ⁻; phosphonium compounds such ashalogenated P compounds, e.g. PF₆ ⁻; and borates such as halo, alkyland/or aryl substituted borate compounds, e.g. B(C₆H₅)₄ ⁻ and BF₄ ⁻.

[0076] Specifically preferred counter anions of PAG compounds of theinvention (group X in above formulae) include:

[0077] 2-acrylamido-2-methyl-1-propanesulfonate;

[0078] 8-anilino-1-naphthylenesulfonate;

[0079] benzylsulfonate;

[0080] t-butanesulfonate;

[0081] 4-t-butylbenzenesulfonate;

[0082] camphorsulfonate;

[0083] di-(2-ethylhexyl)succinatesulfonate;

[0084] 2,6-difluorobenzoate;

[0085] 3,4-dimethoxybenzenesulfonate;

[0086] 5-dimethylamino-1-naphthalenesulfonate;

[0087] 3-(4-dimethylamino-1-naphthylazo)-4-methoxybenzenesulfonate;

[0088] 4-[(4-dimethylamino)phenylazo]benzenesulfonate;

[0089] 2,4-dinitrobenzenesulfonate;

[0090] (2-/3-/4-)-dodecylbenzenesulfonate;

[0091] ethanesulfonate;

[0092] 4-fluorobenzenesulfonate;

[0093] hexadecanesulfonate;

[0094] hexafluorophosphate;

[0095] methanesulfonate;

[0096] 1-naphthalenesulfonate;

[0097] 2-naphthalenesulfonate;

[0098] 4-octylbenzenesulfonate;

[0099] pentafluorobenzenesulfonate;

[0100] pentamethylbenzenesulfonate;

[0101] 4-pyridineethanesulfonate;

[0102] 3-pyridinesulfonate;

[0103] thymol blue;

[0104] toluenesulfonate;

[0105] 2,4,5-trichlorobenzenesulfonate;

[0106] 2,2,2-trifluoroethanesulfonate;

[0107] trifluoromethanesulfonate (triflate);

[0108] trifluoroacetate;

[0109] 2-trifluoromethylbenzenesulfonate;

[0110] 3-trifluoromethylbenzenesulfonate;

[0111] 4-trifluoromethylbenzenesulfonate;

[0112] 3,5-bis(trifluoromethyl)benzeinesulfonate;

[0113] 2,4,6-triisopropylbenzenesulfonate;

[0114] 2,4,6-trimethylbenzenesulfonate;

[0115] perfluoroctanesulfonate;

[0116] perfluorohexanesulfonate;

[0117] perfluorobutanesulfonate; and

[0118] perfluoroethoxyethylsulfonate.

[0119] Of the above, the perfluoroalkyl and perfluoroalkoxy anions areoften preferred such as triflate; perfluorocutanesulfonate;perfluorhexanesulfonate; and perfluoroethoxyethylsulfonate.

[0120] Additional preferred PAGs for use in PAG systems and resists ofthe invention include oxime sulfonate PAGs, preferably wherein the oximecarbon has one or two electron-withdrawing substituents. Preferred oximesulfonate PAGs include those of the following Formula XV:

RR′C=NOS(O)₂Y  XV

[0121] wherein in Formula XV, at least one of R and R′ is anelectron-withdrawing moiety such as cyano, nitro, haloalkyl such ashaloC₁₋₁₆alkyl, particularly fluoroalkyl e.g. perfluoro(C₁₋₁₆)alkyl suchas —CF₃, —CF₂CF₃, and other perfluoralkyl; alkanoyl preferably having 1to about 12 carbon atoms; alkylsulfinyl preferably having 1 to about 12carbon atoms; alkylsulfonyl preferably having 1 to about 12 carbonatoms; and the like;

[0122] if only one of R and R′ is an electron-withdrawing moiety, thenone of R and R′ is suitably optionally substituted carbocyclic aryl suchas optionally substituted phenyl and optionally substituted naphthyl;optionally substituted alkyl preferably having 1 to about 20 carbonatoms; optionally substituted alkenyl preferably having 2 to about 20carbon atoms; optionally substituted alkynyl preferably having 2 toabout 20 carbon atoms; optionally substituted alkoxy preferably having 1to about 20 carbon atoms; optionally substituted heteroalicyclic orheteroaromatic suitably having 1-3 rings with 3-8 ring members per ringand 1-3 N, O or S atoms such as thienyl;

[0123] Y is a non-hydrogen substituent such as optionally substitutedcarbocyclic aryl such as optionally substituted phenyl and optionallysubstituted naphthyl; optionally substituted alkyl preferably having 1to about 20 carbon atoms; optionally substituted alkenyl preferablyhaving 2 to about 20 carbon atoms; optionally substituted alkynylpreferably having 2 to about 20 carbon atoms; optionally substitutedalkoxy preferably having 1 to about 20 carbon atoms; optionallysubstituted heteroalicyclic or heteroaromatic suitably having 1-3 ringswith 3-8 ring members per ring and 1-3 N, O or S atoms such as thienyl.

[0124] In Formula XV, preferably R is an electron-withdrawing group andR′ is an optionally substituted carbocyclic aryl or heteroalicyclic orheteromaromatic group. In Formula XV, particularly preferred R groupsinclude cyano and haloalkyl such as C₁₋₁₆haloalkyl, particularlyfluoroalkyl such as C₁₋₁₆perfluoroalkyl e.g. trifluoromethyl,pentafluorethyl, perfluorbutane and the like. In Formula XV, preferredR′ groups incloude optionally substituted naphthyl, optionallysubstituted thienyl and optionally substituted pentafluorophenyl. InFormula XV, R and R′ may be the same, or more typically R and R′ aredifferent. In Formula XV, preferred Y groups may be electron-withdrawinggroups (to provide a stronger photoacid) such as haloalkyl, particularlyperhalalkyl such as perfluoralkyl e.g. C₁₋₁₆perfluoroalkyl; carbocyclicaryl such as phenyl, naphthyl and the like, particularly substitutedwith one or more electron-withdrawing substituents such as nitro, cyano,halo (especially fluoro) with pentafluorophenyl being particularlypreferred. Electron-donating groups also will be suitable Y groups suchas optionally substituted alkyl e.g. C₁₋₁₂alkyl, although perhaps lesspreferred.

[0125] Additional preferred PAGs for use in PAG systems and resists ofthe invention include N-oxyimidosulfonate PAGs that preferably containtwo or more N-oxyimidosulfonate groups are generally preferred.Bis-N-oxyimidosulfonate compounds are generally preferred, i.e. PAGsthat contain two N-oxyimidosulfonate groups. Also preferred areN-oxyimidosulfonate compounds that do not contain an aromatic group. Inparticular, preferred are compounds of the following Formula XVIA:

[0126] wherein Y′ and Y″ are the same or different non-hydrogensubstituent such as the groups specified for Y in Formula XV above;

[0127] and the dotted lines indicate covalent linkage (to provide asingle compound) between the two N-oxyimidosulfonate groups.

[0128] A variety of linkages between the N-oxyimidosulfnate groups. Forexample, the N-oxyimidosulfonate groups can each form 5, 6, 7, or8-membered fused rings, such as PAGs of the following Formula VXIB:

[0129] wherein Y′ and Y″ are the same or different non-hydrogensubstituent such as the groups specified for Y in Formula XV above;

[0130] m, m′, n, and n′ are each independently 0, 1 or 2, and the sum ofeach of m and m′ and of n and n′ does not exceed 3.

[0131] Generally preferred PAGs of Formula XVIB include those where m,m′, n and, n′ are each zero, i.e. PAGs of the following Formula XVIB′:

[0132] wherein Y′ and Y″ are the same or different non-hydrogensubstituent such as the groups specified for Y in Formula XV above;

[0133] Additional preferred PAGs of Formula XVIA include those where thetwo imidosulfonate groups each form a ring, and with a further ringinterposed between the two imidosulfonate rings. For example, preferredPAGs include those of the following Formula XVIC:

[0134] wherein Y′ and Y″ are the same or different non-hydrogensubstituent such as the groups specified for Y in Formula XV above; m,m, n, and n′ are the same as defined in Formula XVIB above; and thedotted lines designate an alicyclic, carbocyclic aryl, heteroalicyclicor heteroaromatic ring interposed between and fused to the two depictedimidosulfonate rings.

[0135] Preferred PAGs of Formuloa XVIC include those where m, m′, n andn′ are each zero, i.e. PAGs of the following Formula XVIC′:

[0136] wherein Y′ and Y″ are the same or different non-hydrogensubstituent such as the groups specified for Y′ and Y″ in Formula XVIAabove; and the dotted lines designate an alicyclic, carbocyclic aryl,heteroalicyclic or heteroaromatic ring interposed between and fused tothe two depicted imidosulfonate rings.

[0137] Preferred interposed rings fused to imidosulfonate groups includecyclopentyl, cyclohexyl with an optional bridge group and naphthyl, suchas compounds of the following Formula XVICa, XVICb and XVICc:

[0138] wherein in each of Formulae XV, XVICa, XVICb, and XVICc, Y′ andY″ are the same as defined in Formula XVIA; and the dotted line inFormula IICa designiates an optional bridge group such as alkylene oralkenylene groups such e.g. —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, —CH═CH—,—CH₂—CH═CH—, and the like.

[0139] In Formula XVIA, XVIB, XVIB′, XVIC, XVIC′, XVICa, XVICb, andXVICc, preferred Y, Y′ and Y″ groups including electron-withdrawinggroups (to provide a stronger photoacid) such as haloalkyl, particularlyperhalalkyl such as perfluoralkyl e.g. C₁₋₁₆perfluoroalkyl such astrifluormethyl, pentafluoroethyl, perfluorobutylm perfluorobutane, andthe like; carbocyclic aryl such as phenyl, naphthyl and the like,particularly substituted with one or more electron-withdrawingsubstituents such as nitro, cyano, halo (especially fluoro) withpentafluorophenyl being particularly preferred; heteroaromaticparticularly optionally substituted thienyl; and alicyclic andheteroalicyclic groups. In Formula XVIA, XVIB,XVIB′, XVIC, XVIC′, XVICa,IICb, and IICc, electron-donating groups also will be suitable Y′ and Y″groups such as optionally substituted alkyl e.g. C₁₋₁₂alkyl.

[0140] As stated above, various substituent groups of PAGs andsensitizers of PAG systems and resists of the invention may beoptionally substituted. Substituted moieties (including substituted R,X, R¹, and R² groups of the above formulae) are suitably substituted atone or more available positions by, e.g., halogen such as F, Cl Brand/or I, nitro, cyano, sulfono, alkyl including C₁₋₁₆alkyl withC₁₋₈alkyl being preferred, haloalkyl such as fluoroalkyl (e.g.trifluoromethyl) and perhaloalkyl such as perfluoroC₁₋₄alkyl, alkoxyincluding C₁₋₁₆ alkoxy having one or more oxygen linkages withC₁₋₈alkoxy being preferred, alkenyl including C₂₋₁₂alkenyl withC₂₋₈alkenyl being preferred, alkenyl including C₂₋₁₂alkenyl withC₂₋₈alkynyl being preferred, aryl such as phenyl or naphthyl andsubstituted aryl such as halo, alkoxy, alkenyl, alkynyl and/or alkylsubstituted aryl, preferably having the number of carbon atoms mentionedabove for corresponding groups. Preferred substituted aryl groupsinclude substituted phenyl, anthracenyl and naphthyl.

[0141] As used herein, the term alkyl, alkenyl and alkynyl unlessotherwise modified refers to both cyclic and noncyclic groups, althoughof course cyclic groups will comprise at least three carbon ringmembers. Alkenyl and alkynyl groups of compounds of the invention haveone or more unsaturated linkages, typically 1 to about 3 or 4unsaturated linkages. Also, the terms alkenyl and alkynyl as used hereinrefer to both cyclic and noncyclic groups, although straight or branchednoncyclic groups are generally more preferred. Alkoxy groups of PAGcompounds of the invention have one or more oxygen linkages, typically 1to about 5 or 6 oxygen linkages. Alkylthio groups of PAGs of theinvention have one or more thioether linkages, typically 1 to about 5 or6 thioether linkages. Alkylsulfinyl groups of PAG compounds of theinvention have one or more sulfinyl (SO) linkages, typically 1 to about5 or 6 sulfinyl linkages. Alkylsulfonyl groups of PAG compounds of theinvention have one or more sulfonyl (SO₂) linkages, typically 1 to about5 or 6 sulfonyl linkages. Preferred alkylamino groups of PAG compoundsof the invention include those groups having one or more primary,secondary and/or tertiary amine groups, preferably 1 to about 3 or 4amine groups. Suitable alkanoyl groups have one or more carbonyl groups,typically 1 to about 4 or 5 carbonyl groups. Alkoxy, alkylthio,alkylsulfinyl, alkylsulfonyl, alkanoyl and other groups may be suitablyeither linear or branched. Carbocyclic aryl as used herein refers tonon-hetero aromatic groups that have 1 to 3 separate or fused rings and6 to about 18 carbon ring members and may include e.g. phenyl, naphthyl,biphenyl, acenaphthyl, phenanthracyl, and the like. Phenyl and naphthylare often preferred. Suitable heteroaromatic or heteroaryl groups willhave 1 to 3 rings, 3 to 8 ring members in each ring and from 1 to about3 hetero atoms (N, O or S). Specifically suitable heteroaromatic orheteroaryl groups include e.g. courmarinyl, quinolinyl, pyridyl,pyrazinyl, pyrimdinyl, furyl, pyrrolyl, thienyl, thiazolyl, oxazolyl,imidazolyl, indolyl, benzofuranyl, benzothiophene and benzothiazole.

[0142] PAGs of the invention can be readily prepared by known methods.More particularly, sulfonium PAGs of the invention can be prepared e.g.by Grignard reaction with a substituted sulfoxide compound. Thus, forinstance, to prepare a tri-naphthyl sulfonium compound, of an optionallysubstituted naphthyl Grignard reagent, such as naphthyl magnesiumchloride can be reacted with a di-naphthyl sulfoxide (where the naphthylgroups are the same or different). Iodonium compounds of the inventioncan be suitably prepared e.g. by methods disclosed in U.S. Pat. No.5,879,856, Example 2 thereof. Thus, an iodonium PAG of the invention canbe prepared by reaction of a mixture of an iodate such as potassiumiodate, with a thienyl, naphthyl or pentafluorophenyl compound andacetic anhydride with sulfuric acid added suitably dropwise to themixture, preferably at reduced temperatures such as provided by ice-bathcooling. Other compounds can be reacted to provide other substituents ofthe iodonium compound. The reaction mixture then can be suitably stirredat room temperature until substantial reaction completion to provide thedesired cation. The mixture then can be cooled, e.g. to ca. 5-10° C.,and then the anion component is added, e.g. a substituted sulfonic orcarboxylic acid, followed by neutralization with suitable base such asammonium hydroxide. To prepare iodonium PAG compounds having a thienylsubstituent, synthetic methods can be employed as generally described inBeringer et al., Journal of Organic Chemistry, 35(16):2095 (1970). Toprepare iodonium PAG compounds having one or more naphthyl substituents,synthetic methods can be employed as generally described in Beringer etal., Journal of Organic Chemistry, 34(3):685 (1969). To preparesulfonium PAGs of the invention where the sulfonium cation is a ringmember (see Formulae XIII and XIV above), the sulfur ring compound suchas thiophene or thianaphthene can be reacted with another addition groupin the presence of copper benzoate. See generally Examples 1 through 5which follow for preferred syntheses.

[0143] Oxime sulfonate PAGs can be prepared e.g. by reaction of anα-cyano compound of the formula NCCH₂—R wherein R is as defined inFormula XV above with amyl nitrate to provide the coreesponbding oximeof the formula NCC(═NOH)R. That oxime can be reacted with a substitutedsulfonyl chloride (e.g. substituted with a group Y as defined in FormulaXV above) to provide PAGs of Formula XV. N-oxyimidosulfonate PAGs can besuitably prepared e.g. by reaction of a corresponding anhydride such asbis-succnic anhydride with hydroxylamine to provide the correspondingN-hydroxy imide. That N-hydroxy imde then can be reacted with asubstituted sulfonyl chloride (e.g. substituted with a group Y¹ asdefined in Formula XVIA above).

[0144] Thus a PAG of the structure NC(1-naphthyl)C═NOS(O)₂C₆F₅ can beprepared by reaction of NCCH2-(1-naphthyl) with amyl nitrate to providethe oxime NCC(═NOH)(1-naphthyl). That oxime is reacted withpentafluorobenzene sulfonyl chloride to provideNC(1-naphthyl)C═NOS(O)₂C₆F₅.

[0145] As discussed above, PAGs of the invention are useful as theradiation sensitive component in photoresist compositions, includingboth positive-acting and negative-acting chemically amplified resistcompositions.

[0146] The photoresists of the invention typically comprise a resinbinder and a photoactive component of the invention as described above.Preferably the resin binder has functional groups that impart alkalineaqueous developability to the resist composition. For example, preferredare resin binders that comprise polar functional groups such as hydroxylor carboxylate. Preferably the resin binder is used in a resistcomposition in an amount sufficient to render the resist developablewith an aqueous alkaline solution.

[0147] For imaging at wavelengths greater than 200 nm, such as 248 nm,phenolic resins are typically preferred. Preferred phenolic resins arepoly (vinylphenols) which may be formed by block polymerization,emulsion polymerization or solution polymerization of the correspondingmonomers in the presence of a catalyst. Vinylphenols useful for theproduction of polyvinyl phenol resins may be prepared, for example, byhydrolysis of commercially available coumarin or substituted coumarin,followed by decarboxylation of the resulting hydroxy cinnamic acids.Useful vinylphenols may also be prepared by dehydration of thecorresponding hydroxy alkyl phenols or by decarboxylation of hydroxycinnamic acids resulting from the reaction of substituted ornonsubstituted hydroxybenzaldehydes with malonic acid. Preferredpolyvinylphenol resins prepared from such vinylphenols have a molecularweight range of from about 2,000 to about 60,000 daltons.

[0148] Copolymers containing phenol and nonaromatic cyclic alcohol unitsalso are preferred resin binders for resists of the invention and may besuitably prepared by partial hydrogenation of a novolak orpoly(vinylphenol) resin. Such copolymers and the use thereof inphotoresist compositions are disclosed in U.S. Pat. No. 5,128,232 toThackeray et al.

[0149] Additional suitable resins include those formed frombishydroxymethylated compounds, and block novolak resins. See U.S. Pat.Nos. 5,130,410 and 5,128,230 where such resins and use of same inphotoresist compositions is disclosed. Additionally, two or more resinbinders of similar or different compositions can be blended or combinedtogether to give additive control of lithographic properties of aphotoresist composition. For instance, blends of resins can be used toadjust photospeed and thermal properties and to control dissolutionbehavior of a resist in a developer.

[0150] Preferably, a photoacid generator compound of the invention isemployed in a chemically amplified positive-acting resist. A number ofsuch resist compositions have been described, e.g., in U.S. Pat. Nos.4,968,581; 4,883,740; 4,810,613 and 4,491,628 and Canadian PatentApplication 2,001,384, all of which are incorporated herein by referencefor their teaching of making and using chemically amplifiedpositive-acting resists. In accordance with the present invention, thoseprior resist compositions are modified by substitution of thephotoactive component of the invention as the radiation sensitivecomponent.

[0151] For imaging at wavelengths greater than 200 nm, such as 248 nm, aparticularly preferred chemically amplified photoresist of the inventioncomprises in admixture a photoactive component of the invention and aresin binder that comprises a copolymer containing both phenolic andnon-phenolic units. For example, one preferred group of such copolymershas acid labile groups substantially, essentially or completely only onnon-phenolic units of the copolymer, particularly alkylacrylatephotoacid-labile groups, i.e. a phenolic-alkyl acrylate copolymer. Oneespecially preferred copolymer binder has repeating units x and y of thefollowing formula:

[0152] wherein the hydroxyl group be present at either the ortho, metaor para positions throughout the copolymer, and R′ is substituted orunsubstituted alkyl having 1 to about 18 carbon atoms, more typically 1to about 6 to 8 carbon atoms. Tert-butyl is a generally preferred R′group. An R′ group may be optionally substituted by e.g. one or morehalogen (particularly F, Cl or Br), C₁₋₈alkoxy, C₂₋₈ alkenyl, etc. Theunits x and y may be regularly alternating in the copolymer, or may berandomly interspersed through the polymer. Such copolymers can bereadily formed. For example, for resins of the above formula, vinylphenols and a substituted or unsubstituted alkyl acrylate such ast-butylacrylate and the like may be condensed under free radicalconditions as known in the art. The substituted ester moiety, i.e.R′—O—C(═O)—, moiety of the acrylate units serves as the acid labilegroups of the resin and will undergo photoacid induced cleavage uponexposure of a coating layer of a photoresist containing the resin.Preferably the copolymer will have a M_(w) of from about 8,000 to about50,000, more preferably about 15,000 to about 30,000 with a molecularweight distribution of about 3 or less, more preferably a molecularweight distribution of about 2 or less. Non-phenolic resins, e.g. acopolymer of an alkyl acrylate such as t-butylacrylate ort-butylmethacrylate and a vinyl alicyclic such as a vinyl norbornanyl orvinyl cyclohexanol compound, also may be used as a resin binder incompositions of the invention. Such copolymers also may be prepared bysuch free radical polymerization or other known procedures and suitablywill have a M_(w) of from about 8,000 to about 50,000, and a molecularweight distribution of about 3 or less.

[0153] Another preferred resin binder for a positive chemicallyamplified resist of the invention has phenolic and nonaromatic cyclicalcohol units, wherein at least of portion of the hydroxyl groups of thecopolymer are bonded to acid labile groups. Preferred acid labilemoieties are acetate groups including t-butyl acetate groups of theformula (CH₃)₃COC(O)CH₂—; oxycarbonyl groups such as t-butyl oxycarbonyl(t-Boc) groups of the formula (CH₃)₃CC(O)O—; and acetal and ketals.Chemically amplified positive-acting photoresists containing such acopolymer have been disclosed in U.S. Pat. No. 5,258,257 to Sinta et al.

[0154] Other preferred resins that have acid-labile deblocking groupsfor use in a positive-acting chemically-amplified photoresist of theinvention have been disclosed in European Patent Application 0829766A2of the Shipley Company (resins with acetal and ketal resins) andEuropean Patent Application EP0783136A2 of the Shipley Company(terpolymers and other copolymers including units of 1) styrene; 2)hydroxystyrene; and 3) acid labile groups, particularly alkyl acrylateacid labile groups such as t-butylacrylate or t-butylmethacrylate). Ingeneral, resins having a variety of acid labile groups will be suitable,such as acid sensitive esters, carbonates, ethers, imides, etc. Thephotoacid labile groups will more typically be pendant from a polymerbackbone, although resins that have acid labile groups that are integralto the polymer backbone also may be employed.

[0155] PAG systems of the invention also are preferably used withpolymers that contain one or more photoacid-labile groups and that aresubstantially, essentially or completely free of phenyl or otheraromatic groups. Such photoresist compositions are particularly usefulfor imaging with sub-200 nm radiation such as 193 nm radiation.

[0156] For example, preferred polymers contain less than about 5 molepercent aromatic groups, more preferably less than about 1 or 2 molepercent aromatic groups, more preferably less than about 0.1, 0.02, 0.04and 0.08 mole percent aromatic groups and still more preferably lessthan about 0.01 mole percent aromatic groups. Particularly preferredpolymers are completely free of aromatic groups. Aromatic groups can behighly absorbing of sub-200 nm radiation and thus are undesirable forpolymers used in photoresists imaged with such short wavelengthradiation.

[0157] Suitable polymers that are substantially or completely free ofaromatic groups and may be formulated with a PAG of the invention toprovide a photoresist for sub-200 nm imaging are disclosed in Europeanapplication EP930542A1 of the Shipley Company.

[0158] Suitable polymers that are substantially or completely free ofaromatic groups suitably contain acrylate units such as photoacid-labileacrylate units as may be provided by polymerization ofmethyladamantylacrylate, methyladamantylmethacrylate,ethylfenchylacrylate, ethylfenchylmethacrylate, and the like; fusednon-aromatic alicyclic groups such as may be provided by polymerizationof a norbornene compound or other alicyclic compound having anendocyclic carbon-carbon double bond; an anhydride such as may beprovided by polymerization of maleic anhydride; and the like.

[0159] Preferred negative-acting compositions of the invention comprisea mixture of materials that will cure, crosslink or harden upon exposureto acid, and a photoactive component of the invention.

[0160] Particularly preferred negative acting compositions comprise aresin binder such as a phenolic resin, a crosslinker component and aphotoactive component of the invention. Such compositions and the usethereof has been disclosed in European Patent Applications 0164248 and0232972 and in U.S. Pat. No. 5,128,232 to Thackeray et al. Preferredphenolic resins for use as the resin binder component include novolaksand poly(vinylphenol)s such as those discussed above. Preferredcrosslinkers include amine-based materials, including melamine,glycolurils, benzoguanamine-based materials and urea-based materials.Melamine-formaldehyde resins are generally most preferred. Suchcrosslinkers are commercially available, e.g. the melamine resins soldby American Cyanamid under the trade names Cymel 300, 301 and 303.Glycoluril resins are sold by American Cyanamid under trade names Cymel1170, 1171, 1172, urea-based resins are sold under the trade names ofBeetle 60, 65 and 80, and benzoguanamine resins are sold under the tradenames Cymel 1123 and 1125.

[0161] Photoresists of the invention also may contain other materials.For example, other optional additives include actinic and contrast dyes,anti-striation agents, plasticizers, speed enhancers, sensitizers (e.g.for use of a PAG of the invention at longer wavelengths such as I-line(i.e. 365 nm) or G-line wavelengths), etc. Such optional additivestypically will be present in minor concentration in a photoresistcomposition except for fillers and dyes which may be present inrelatively large concentrations such as, e.g., in amounts of from 5 to30 percent by weight of the total weight of a resist's dry components.

[0162] A preferred optional additive of resists of the invention is anadded base, particularly tetrabutylammonium hydroxide (TBAH), which canenhance resolution of a developed resist relief image. The added base issuitably used in relatively small amounts, e.g. about 1 to 10 percent byweight relative to the PAG, more typically 1 to about 5 weight percent.Other preferred basic additives include ammonium sulfonate salts such aspiperidinium p-toluenesulfonate and dicyclohexylammoniump-toluenesulfonate; alkyl amines such as tripropylamine anddodecylamine; aryl amines such as diphenylamine, tnphenylamine,aminophenol, 2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane, etc.

[0163] The resin binder component of resists of the invention aretypically used in an amount sufficient to render an exposed coatinglayer of the resist developable such as with an aqueous alkalinesolution. More particularly, a resin binder will suitably comprise 50 toabout 90 weight percent of total solids of the resist. The photoactivecomponent should be present in an amount sufficient to enable generationof a latent image in a coating layer of the resist. More specifically,the photoactive component will suitably be present in an amount of fromabout 1 to 40 weight percent of total solids of a resist. Typically,lesser amounts of the photoactive component will be suitable forchemically amplified resists.

[0164] The photoresists of the invention are generally preparedfollowing known procedures with the exception that a PAG system of theinvention is substituted for prior photoactive compounds used in theformulation of such photoresists. For example, a resist of the inventioncan be prepared as a coating composition by dissolving the components ofthe photoresist in a suitable solvent such as, e.g., a glycol ether suchas 2-methoxyethyl ether (diglyme), ethylene glycol monomethyl ether,propylene glycol monomethyl ether and propylene glycol monomethyl etheracetate; lactates such as ethyl lactate or methyl lactate, with ethyllactate being preferred; propionates, particularly methyl propionate,ethyl propionate and 3-ethyl ethoxypropionate; a Cellosolve ester suchas methyl Cellosolve acetate; an aromatic hydrocarbon such toluene orxylene; or a ketone such as methylethyl ketone, cyclohexanone and2-heptanone. Typically the solids content of the photoresist variesbetween 5 and 35 percent by weight of the total weight of thephotoresist composition.

[0165] The photoresists of the invention can be used in accordance withknown procedures. Though the photoresists of the invention may beapplied as a dry film, they are preferably applied on a substrate as aliquid coating composition, dried by heating to remove solventpreferably until the coating layer is tack free, exposed through aphotomask to activating radiation, optionally post-exposure baked tocreate or enhance solubility differences between exposed and nonexposedregions of the resist coating layer, and then developed preferably withan aqueous alkaline developer to form a relief image.

[0166] The substrate on which a resist of the invention is applied andprocessed suitably can be any substrate used in processes involvingphotoresists such as a microelectronic wafer. For example, the substratecan be a silicon, silicon dioxide or aluminum-aluminum oxidemicroelectronic wafer. Gallium arsenide, ceramic, quartz or coppersubstrates may also be employed. Printed circuit board substrates suchas copper clad laminates are also particularly preferred. Thephotoresists of the invention will be particularly useful for circuitboard imaging, including through hole and other aperture plating.Typical printed circuit board substrates have one or more copper layersinterleaved with resin layers, such as epoxy layers.

[0167] Substrates used for liquid crystal display and other flat paneldisplay applications are also suitably employed, e.g. glass substrates,indium tin oxide coated substrates and the like.

[0168] A liquid coating resist composition may be applied by anystandard means such as spinning, dipping or roller coating. Photoresistsof the invention also may be formulated and applied as dry film resists,particularly for printed circuit board manufacture applications. Theexposure energy should be sufficient to effectively activate thephotoactive component of the radiation sensitive system to produce apatterned image in the resist coating layer. Suitable exposure energiestypically range from about 1 to 300 mJ/cm². As discussed above,preferred exposure wavelengths include sub-300 nm such as 248 nm, andsub-200 nm such as 193 nm and 157 nm. Suitable post-exposure baketemperatures are from about 50° C. or greater, more specifically fromabout 50 to 150° C. For an acid-hardening negative-acting resist, apost-development bake may be employed if desired at temperatures of fromabout 100 to 150° C. for several minutes or longer to further cure therelief image formed upon development. After development and anypost-development cure, the substrate surface bared by development maythen be selectively processed, for example chemically etching or platingsubstrate areas bared of photoresist in accordance with procedures knownin the art. Suitable etchants include a hydrofluoric acid etchingsolution and a plasma gas etch such as an oxygen plasma etch.

[0169] All documents mentioned herein are incorporated herein byreference. The following non-limiting example is illustrative of theinvention.

Examples 1-3 Sensitization testing.

[0170] Photoacid generator compound-sensitizer combinations wereevaluated for radiation sensitivity. The following determinations weremade:

[0171] 1) the photospeed of the PAG/sensitizer combination isdetermined;

[0172] 2) the photospeed of an identical sample without sensitizer isalso determined. The comparison between these two photospeeds indicateswhether there is any sensitization happening (sensitized sample hasfaster photospeed) or not (photospeed of sensitizer sample is slowerthan PAG-alone sample);

[0173] 3) the photospeed of a sample containing no sensitizer where thePAG amount was adjusted so that its absorbance matches that of thesensitized sample is determined. If the photospeed of this adjusted PAGsample is still slower than that of the sensitized sample, sensitizationis not only happening but actually more efficient than direct photolysisof the PAG.

[0174] The following table contains two examples of sensitizer PAGcombinations where sensitization offers an advantage over directexcitation (examples 1 and 2). Results of a third system (example 3) arealso shown. E0 for E0 for no E0 for sensitizer/ sensitizer/ adjusted PAGsame PAG PAG Photoacid generator Sensitizer combination amount amountN-trifluoromethanesulfonyloxy-5- hexahydro 7.3 14.1 9.2norbornene-2,3-dicarboximide pyrene (example 1) dithienyliodoniumhexahydro 13.2 19.3 15.6 perfluorobutanesulfonate pyrene (example 2)S-(2,3,4-trimethoxyphenyl)- 1,6-dihydroxy 7.0 12.4 —tetramethylenesulfonium triflate naphthalene (example 3)

Example 4 Resist preparation and lithographic processing.

[0175] A resist formulation comprising a copolymer of2-methyl-2-adamantyl methacrylate and β-butyrolactone methacrylate(13.07 g of a 30 wt. % solution in 2-heptanone),N-trifluoromethanesulfonyloxy-5-norbornene-2,3-dicarboximide (0.146 g),hexahydropyrene (0.22 g), base additive (0.40 g of a 1 wt. % solution in2-heptanone), a surfactant ( 0.40 g of a 1 wt. % solution in2-heptanone) and 11.06 g 2-heptanone was prepared. The resultingsolution was spin coated onto 820 Å thick AR19 (215° C./90 sec) coatedsilicon wafers (150 mm) on a Polaris system and baked (proximity) at120° C. for 60 seconds to form a resist film having a thickness of3900+/−25 Å. The resulting wafers were exposed on an ISI microstepperstepper under conventional illumination conditions. The wafers werepost-exposure baked at 120° C. for 60 seconds then developed in LDD-26using a 60 second single puddle process and the dose to cleardetermined.

[0176] Control samples without the sensitizer and a) the same PAGloading and b) with adjusted PAG loading were formulated and processedin the same way, except that no sensitizer was added and the PAG amountkept the same (a) or increased to 0.216 g (b).

EXAMPLES 5-9 Syntheses of photoacid generator compounds Example 5

[0177] Preparation of di(1-naphthyl)phenylsulfonium triflate

[0178] Under a nitrogen atmosphere, anhydrous sodium sulfide (4.3 g,0.055 mole) and CuI (1.9 g, 0.010 mole) is added to a solution of1-iodonaphthalene (27.9 g, 0.110 mole) in 100 ml dry THF and thesolution is refluxed for 24 h. After cooling, 500 ml water is added andthe mixture extracted three times with dichloromethane (100 ml). Thecombined organic phases are washed with 2N NaOH (3×50 mL), dried and thesolvent is removed. The brownish-yellow crude product is purified bycolumn chromatography on silica gel (ethylacetate/cyclohexane 1:4),yielding 6 g (30%) of the sulfide as a white solid. The structure wasconfirmed by ¹H/¹³C NMR spectroscopy.

[0179] Di(1-naphthyl)sulfide (3 g, 0.0104 mole), diphenyliodoniumtriflate (5.8 g, 0.0135 mole) and copperbenzoate (0.08 g, 0.003 mole)are heated without solvent for 3 hours at 120-145° C. under a nitrogenatmosphere. After cooling down, 75 ml ether was added and the mixturevigorously stirred overnight to achive solidification. Filtration andwashing with ether yielded a brown solid, which was dissolved in hotwater, the solution filtered and the water removed in vacuo. Theresulting white solid was stirred in 50 ml ethyl ether for 24 hours, themixture filtered and the residue washed with ethyl ether, yielding 4.8 g(90%) of the title compound, di-(1-naphtyl)phenylsulfonium triflate. Thestructure was confirmed by ¹H/¹³C NMR spectroscopy.

Example 6 Preparation of (2-thienyl)diphenylsulfonium triflate

[0180]

[0181] (2-thienyl)phenylsulfinde (2.0 g, 0.0104 mole), diphenyliodoniumtriflate (5.8 g, 0.0135 mole) and copper benzoate (0.08 g, 0.003 mole)are heated without solvent for 3 hours at 120-145° C. under nitrogenatmosphere. After cooling dow 75 ml ethyl ether was added and themixture vigorously stirred overnight to achieve solidification.Filtration and washing with ethyl ether yielded a brown solid, which wasdissolved in hot water, the solution filtered and the water removed invacuo. The resulting white solid was stirred in 50 ml ether for 24hours, the mixture filtered and the residue washed with ethyl ether,yielding, 3.9 g (90%) of the title compound,(2-thienyl)diphenylsulfonium triflate. The structure was confirmed by¹H/¹³CMR

Example 7 Preparation of di-(2-thienyl)phenylsulfonium triflate

[0182]

[0183] Di-(2-thienyl)sulfide (2.1 g, 0.0104 mole), diphenyliodoniumtriflate (5.8 g, 0.0135 mole) and copper benzoate (0.08 g, 0.003 mole)are heated without solvent for 3 hours at 120-145° C. under a nitrogenatmosphere. After cooling down, 75 ml ethyl ether was added and themixture vigorously stirred overnight to achieve solidification.Filtration and washing with ethyl ether yielded a brown solid, which wasdissolved in hot water, the solution filtered and the water removed invacuo. The resulting white solid was stirred in 50 ml ethyl ether for 24hours, the mixture filtered and the residue washed with ethyl ether,yielding 3.4 g (78%) of the title compound, di(2-thienyl)phenylsulfoniumtriflate. The structure was confirmed by ¹H/¹³C NMR spectroscopy.

Example 8 Preparation of di(pentafluorophenyl)phenylsulfonium triflate

[0184] To thionyl chloride (4 ml, 0.055 mole) in 12 ml ethyl ether isdropwise added a 0.5 M solution of pentafluorophenylmagnesium bromide inethyl ether (100 g, 0.05 mole) at −25° C. with stirring. After theaddition is complete, the mixture is allowed to warm to room temperatureand the stirring is continued for 1 hour. The mixture is filtered,washed with water twice, dried over magnesium sulfate and the solventremoved in vacuo, yielding a brown solid. The residue from thefiltration is dissolved in ethyl ether/water again, the phases areseparated and the ethyl ether layer washed with water twice, dried overmagnesium sulfate and the solvent removed in vacuo, yielding more crudeproduct. The purification was done by sublimation and subsequentrecrysallization from cyclohexane, yielding 6.9 g (72%) of the sulfoxideas a white solid.

[0185] A 3M solution of phenylmagnesium bromide in ether (17 ml, 0.05mole) is heated slowly to 80° C. under vacuum to remove the ether. 8 mlbenzene and 17 ml heptane were then added and subsequentlypentafluorophenyl sulfoxide (3.8 g, 0.01 mole), dissolved in 15 mlbenzene, was added dropwise at 80° C. over one hour. After stirring forthree hours, the solution is allowed to cool to room temperature,followed by the addition of 33 ml of 25% triflic acid. The organic layerwas seprated and extracted twice with 10 ml of 5% triflic acid. Theaqueous layers were combined and extracted three times with 100 mldiclhoromethane and solvent removed after drying over magnesium sulfate,yielding 600 mg (10%) of di(pentafluorophenyl)phenyl sulfonium triflate.The structure was confirmed by ¹H/¹³C NMR.

Example 9 Preparation of 1-phenyl-2-methylbenzothiophenium triflate

[0186]

[0187] 2-Methylthianaphthene (5 g 0.0327 mole), diphenyliodoniumtriflate (18.28 g, 0.0425 mole) and copper benzoate (0.1 g, 0.000327mole) were heated without solvent for 0.5 hours at 140° C. under anitrogen atmosphere. After cooling down, 150 ethyl ether was added tosolidify the product. Filtration and washing with ethyl ether Yielded abrownish-grey solid, which was dissolved in 500 ml hot water, and thesolution filtered and the water removed in vacuo. The resultingoff-white solid was stirred in 50 ml ethyl ether for 1 hour, the mixturefiltered and the residue washed with ethyl ether. The product wasrecrystallized from dichloromethane/t-butyl methyl ether to yield 8.97 g(76%) of 1-phenyl-2-methylbenzothiophenium triflate. The structure wasconfirmed by ¹H/¹³C NMR spectroscopy.

[0188] The foregoing description of the invention is merely illustrativethereof, and it is understood that variations and modifications can beeffected without departing from the spirit or scope of the invention asset forth in the following claims.

What is claimed is:
 1. A method for forming a photoresist relief imageon a substrate comprising: (a) applying a coating layer of achemically-amplified positive photoresist composition on a substrate,the photoresist composition comprising a resin and a photacid generatorcompound and a sensitizer compound; and (b) exposing the photoresistcoating layer to patterned activating radiation having a wavelength ofless than about 200 nm and developing the exposed photoresist layer toprovide a relief image.
 2. The method of claim 1 wherein the sensitizeris a separate component of the photoresist composition.
 3. The method ofclaim 1 or 2 wherein the sensitizer is an aromatic compound.
 4. Themethod of any one of claims 1 through 3 wherein the sensitizer is acarbocyclic aryl compound.
 5. The method of any one of claims 1 through4 wherein the sensitizer is a heteroaromatic compound.
 6. The method ofany one of claims 1 through 5 wherein the sensitizer has from 1 to 3separate or fused rings.
 7. The method of any one of claims 1 through 6wherein the photoacid generator compound is an onium compound or anon-ionic compound.
 8. The method of any one of claims 1 through 7wherein the photoacid generator compound is an iodonium or sulfoniumphotoacid generator compound which has one or more cation substituentsselected from the group consisting of optionally substituted naphthyl,optionally substituted thienyl and pentafluorophenyl.
 9. The method ofclaim 1 wherein the photoacid generator comprises a sulfonium compoundwith the sulfur ration being a ring member.
 10. The method of any one ofclaims 1 through 9 wherein the photoacid generator compound is anon-ionic oxime sulfonate compound or a non-ionic N-oxyimidosulfonatecompound.
 11. The method of any one of claims 1 through 10 wherein thephotoacid generator is a compound of any one of Formula I through XIV,XIVA, XV, XVIA, XVIB, XVIB′, XVIC, XVIC′, XVICa, XVICb, and XVICc. 12.The method of any one of claims 1 through 11 wherein the photoresistcoating layer is exposed to radiation having a wavelength of about 193nm.
 13. A photoresist composition comprising a resin and and a photoacidgenerator system, the system comprising a sensitizer compound and aphotoacid generator compoiund that is 1) an iodonium or sulfoniumphotoacid generator compound which has one or more cation substituentsselected from the group consisting of optionally substituted naphthyl,optionally substituted thienyl and pentafluorophenyl, or 2) a non-ionicoxime sulfonate compound or a non-ionic N-oxyimidosulfonate compound.14. The photoresist of claims 13 wherein the sensitizer is a separatecomponent of the photoresist composition.
 15. The photoresist of claims13 or 14 wherein the sensitizer is an aromatic compound.
 16. Thephotoresist of any one of claims 13 through 15 wherein the sensitizer isa carbocyclic aryl compound.
 17. The photoresist of any one of claims 13through 16 wherein the sensitizer is a heteroaromatic compound.
 18. Thephotoresist of any one of claims 13 through 17 wherein the sensitizerhas from 1 to 3 separate or fused rings.
 19. The photoresist of any oneof claims 13 through 18 wherein the photoacid generator comprises asulfonium compound with the sulfur cation being a ring member.
 20. Thephotoresist of any one of claims 13 through 18 wherein the photoacidgenerator is a compound of any one of Formulae I through XIV, XIVA, XV,XVIA, XVIB, XVIB′, XVIC, XVIC′, XVICa, XVICb, and XVICc, as thoseformulae are defined above.
 21. The photoresist of any one of claims 13through 20 wherein the composition is a chemically amplifiedpositive-acting photoresist.
 22. The photoresist of claim 21 wherein theresin comprises a polymer that contains phenolic and photoacid-labilealkyl acrylate units.
 23. The photoresist of claim 21 wherein the resincomprises a polymer that contains 1) phenolic units, 2) phenyl unitsthat are do not have hydroxy or carboxy ring substituents, and 3)photoacid-labile alkyl acrylate units.
 24. The photoresist of claim 21wherein the resin comprises acetal or ketal groups.
 25. The photoresistof claim 21 wherein the photoresist is essentially free of polymerscontaining aromatic units.
 26. The photoresist composition of any one ofclaims 13 through 20 wherein the composition is a negative-actingphotoresist.
 27. A method for forming a photoresist relief image on asubstrate comprising: (a) applying a coating layer of a photoresistcomposition of any one of claims 13 through 26 on a substrate; and (b)exposing the photoresist coating layer to patterned activating radiationand developing the exposed photoresist layer to provide a relief image.28. The method of claim 27 wherein the photoresist coating layer isexposed to radiation having a wavelength of less than about 300 nm. 29.The method of claim 27 wherein the photoresist coating layer is exposedto radiation having a wavelength of less than about 200 nm.
 30. Themethod of claim 27 wherein the photoresist coating layer is exposed toradiation having a wavelength of about 248 nm, 193 nm or 157 nm.
 31. Anarticle of manufacture having on at least one surface a coating layer ofthe photoresist composition of any one of claims 13 through
 26. 32. Anarticle of manufacture comprising a microelectronic wafer or flat paneldisplay substrate that has on at least one surface a coating layer of aphotoresist of any one of claims 13 through
 26. 33. A photoacidgenerator system comprising a sensitizer compound and a photacidgenerator, the photoacid generator having a substituent selected fromthe group consisting of optionally substituted naphthyl, optionallysubstituted thienyl and pentafluorophenyl, or the photoacid generator isa sulfonioum compound with the sulfonium atom being a member of anoptionally substituted thienyl group.
 34. The photoacid generatorsensitizer of claim 33 wherein the photoacid generator is of theFormulae I through XIV, XIVA, XV, XVIA, XVIB, XVIB′, XVIC, XVIC′, XVICa,XVICb, and XVICc.